When Olive and some of her year 6 friends find themselves locked overnight inside Flatpack - a new IKEA-style superstore - they quickly realise that they are not alone. A number of things hitched a ride from the forest where Flatpack sources its wood and in every dark nook, they've been multiplying...
After several of the group get themselves dragged off to who knows where, Olive knows she was right all along - monsters are definitely real. After that, she's forced to face her fears and come up with a plan: 1) rescue her friends 2) avoid being apprehended by overly efficient store employees, 3) hack into the store's delivery system and send the monsters back where they came from.
Oh, and don't get eaten. Whatever you do, don't look under the beds. And if you hear a wardrobe creaking open behind you, RUN!